This invention relates to thread rolling attachments for screw machines, and more particularly to improved means for controlling the operation of such attachments.
U.S. Pat. No. 4,617,816, which is assigned to the same assignee as this application, discloses a thread rolling attachment having a fluid pressure operated control mechanism for swinging a pair of cooperating threading rolls into and out of operative engagement with the periphery of a piece of rotating bar stock in an automatic screw machine. The threading rolls are carried on the operating ends of a pair of pivotally mounted arms, the opposite ends of which are spring-loaded in a direction normally to maintain the threading rolls disengaged from the work that is to be threaded. A fluid pressure operated piston moves a wedge-shaped operating element between the spring-loaded ends of the arms selectively to cause the arms to pivot the threading rolls into engagement with the work.
While the thread rolling attachment disclosed in the above-noted U.S. Pat. No. 4,617,816 functions effectively for the purpose intended, it is an object of this invention to provide therefor an improved fluid pressure control mechanism which is substantially less complicated, and thus more inexpensive to manufacture and easier to assemble.
Still another object of this invention is to provide for a fluid pressure operated thread rolling attachment of the type described an improved control mechanism which permits more reliable adjustment of the mechanism, and which minimizes the possibility of its failure during use.
Other objects of the invention will be apparent hereinafter from the specification, and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.